Systematic study of Ce3+ on the structural and magnetic properties of Cu nanosized ferrites for potential applications

Systematic study of Ce3+ on the structural and magnetic properties of Cu nanosized ferrites for potential applications

Accepted Manuscript 3+ Systematic Study of Ce on the Structural and Magnetic Properties of Cu Nanosized Ferrites for Potential Applications Majid Niaz...

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Accepted Manuscript 3+ Systematic Study of Ce on the Structural and Magnetic Properties of Cu Nanosized Ferrites for Potential Applications Majid Niaz Akhtar, A.B. Sulong, M.N. Akhtar, Muhammad Azhar Khan PII:

S1002-0721(17)30089-3

DOI:

10.1016/j.jre.2017.09.003

Reference:

JRE 80

To appear in:

Journal of Rare Earths

Received Date: 10 April 2017 Revised Date:

30 August 2017

Accepted Date: 4 September 2017

Please cite this article as: Akhtar MN, Sulong AB, Akhtar MN, Azhar Khan M, Systematic Study of 3+ Ce on the Structural and Magnetic Properties of Cu Nanosized Ferrites for Potential Applications, Journal of Rare Earths (2017), doi: 10.1016/j.jre.2017.09.003. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT

Systematic Study of Ce3+on the Structural and Magnetic Properties of Cu Nanosized Ferrites for Potential Applications Majid Niaz Akhtara,*, A. B. Sulongb, M. N. Akhtarc,*, Muhammad Azhar Khand a

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Department of Physics, Muhammad Nawaz Sharif University of Engineering and Technology (MNSUET), 60000 Multan, Pakistan. b Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM), 43600, Bangi, Selangor, Malaysia. c Institue of Pure and Applied Biology, Department of Zoology, Bahaudin Zakariya University, Multan, 60000 Pakistan. d Department of Physics, The Islamia University of Bahawalpur, Bahawalpur-63100, Pakistan.

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Corresponding author: [email protected], [email protected], [email protected], Tel:+923336856069

ABSTRACT

Ce3+ substituted Cu-spinel nanoferrites CuCexFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) were

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synthesized via sol gel self-combustion hybrid route. Single phase spinel ferrite of Cu nanoferrites were examined using X-ray diffraction (XRD) analysis whereas as the multiphase structure was observed as Ce contents increased from x=0.06 in Cu ferrite. Field emission scanning electron microscopy (FESEM), Thermo gravimetric and differential thermal analysis (TGA and DTA) and Fourier transform infrared spectroscopy (FTIR) were used to find out the morphology phase and metal stretching vibrations of Ce3+ substituted nanocrystalline ferrites. The crystallite size was increased and found in the range of 25-91 nm. The agglomerations in Cu ferrite samples increased as the Ce3+ concentration increased. The magnetic

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properties such as remanence, saturation magnetization, coercivity, Bohr magneton and magnetocrystalline anisotropy constant (K) were determined using M-H loops recorded from vibrating sample magnetometer (VSM). Saturation magnetization, remanence and coercivity were increased as the Ce3+ contents increased in Cu nanocrystalline samples. Moreover, law of approach to saturation (LoA) was used to calculate the maximum value of saturation for Ce-doped Cu nanoferrites. The soft magnetic behaviour of the Cu

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nanoferrite was observed as compared to the samples substituted with the increased Ce contents in Cu nanocrystalline ferrite. Bohr magneton and magnetocrystalline anisotropy were found to increase with the

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substitution of rare earth Ce3+ contents in Cu spinel nanocrystalline ferrite. Ce-doped Cu nanocrystalline ferrites with excellent properties may suitable for potential applications in sensing, security, switching, core, multilayer chip inductor, biomedical and microwave absorption applications. .

Keywords: Ce-doped Cu nanocrystalline ferrites; XRD (X-ray Diffraction); Scanning Electron Microscopy (SEM); Transmission Electron Microscopy (TEM); FTIR (Fourier Transform Infrared Spectroscopy);VSM (Vibrating Sample Magnetometer); LOA (Law of Approach).

[email protected], [email protected], +923336856069

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1. Introduction Magnetic nanoferrites have been paid much attention due to their potential and versatile technological industrial applications in many fields. Spinel ferrites are important magnetic materials because of their excellent structural, mechanical, morphological, chemical and magnetic characteristics [1,2]. Currently,

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magnetic nanoferrites have been used in biomedical, electronics and industrial fields for their potential applications such as target drug delivery, magnetic resonance imaging, oscillators, filters, magnetic switches, magnetic transformer cores, multi-layer chip inductors (MLCIs), high-density data storage, magnetic ferrofluids, high sensitive sensors, antennas, magnetoelectric domain switching, microwave absorbers and high frequency devices and their components [3,4]. The crystal structure of spinel nanoferrites with cubic structure of oxygen ions consists of 32 octahedral sites (B) and 64 tetrahedral sites

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(A). However, metal cations occupy the 16 octahedral sites and 8 tetrahedral sites. Therefore, most of the interstitial sites are empty in the spinel structure for the cations [5]. The properties of the spinel nanoferrites

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are strongly dependent on the chemical composition, preparation, morphology, crystallite size, lattice strain, dopants, distribution of metal cations on the lattice sites and sintering temperature [6]. Moreover, spinel nanoferrites have better chemical and physical properties because of their thermal stability, large surface to volume ratio, surface anisotropy, super paramagnetic behaviour, spin canting, Debye temperature, lattice strain, dislocations of atoms in crystal lattice and accumulation of atoms at grain boundaries [7-9]. The soft and hard character of the nanoferrites play an important role for their use in different applications such as biomedical for target delivery, adsorption, recording, data storage and

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MLCI's. Therefore, it is essential to tune the properties of the nanoferrites according to the requirements. The magnetic properties can be tailored by making variation in the chemical composition, concentration, size of particles, controlled morphology and magnetic phases in the magnetic materials [10]. Therefore, it has been great interest for the scientist to prepare new magnetic nanoferrrites with better electric and magnetic performance which results variety in structural and magnetic properties for versatile

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applications. Various investigations introduced that the substitution and sintering process are very effective and can control the structural and magnetic properties of the nanoferrites [11-13]. A small amount of doping for rare earth ions in the ferrite structure can tune and improve the structural,

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morphological and magnetic properties of the magnetic nanoferrites. The properties of the nanoferrites depend on the type of cations and the distribution of the metal cations on the lattice sites. The previous studies also revealed that the combination of Ce rare earth ions and transition metal ions along with Fe ions in spinel structure may produce excellent magnetic properties for variety of applications. Different researchers have adopted different techniques for the preparation of spinel nanoferrites. In recent years, chemical wet methods have been used to synthesize the spinel nanoferrites because of their better final products. The synthesis techniques include hydrothermal, microwave method, self-combustion, sol-gel, solgel auto combustion, mechanical alloying, glass crystallization method, co-precipitation methods[14-18]. Sol-gel technique has been found better due to their fine surface morphology, low temperature synthesis, excellent properties and better homogeneity of mono dispersed particles[19].

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Cu ferrite has cubic close packed structure with tetrahedral and octahedral sites lattice sites (A and B sites) respectively. The electromagnetic properties depend on the position ionic radii and the distribution of the metal cations on the lattice sites respectively. The exchange of electrons during Fe-Fe interaction on the A and B sites produce changes in the properties of the nanoferrites. However, rare earth ions along with the Fe and metal transition may result unique properties [20]. In this context, Ce is used in Cu ferrites due to

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many functional active sites and large surface area [21]. To the best of our knowledge, a few researchers discussed the role of Ce in Cu ferrite. However, the systematic study of Ce contents on Cu spinel nanoferrites related to their structural and magnetic properties are not evaluated. Moreover, the detailed magnetic analysis for this nanoferrite system is also not studied yet.

In the present study, we have synthesised Ce-doped copper nanoferrites using sol-gel technique. The

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prepared nanoferrites are characterized by different experimental techniques such as X-ray diffraction analysis, FESEM and VSM to find out the structural, morphological and magnetic characteristics. The Law of approach to saturation was applied to investigate the saturation magnetization data. The main objective

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of doping the Ce in Cu ferrite system is to improve the properties include structural, morphological and magnetic of spinel ferrites for a variety of applications such as core, filters, phase shifters, circulators, switches, electromagnetic compatible devices and multilayer chip inductors (MLCI's) components and devices fabrication.

2. Materials and Methods 2.1 Materials

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Copper nitrate (Cu(No3)3.H2O), cerium nitrate (Ce(NO3)2.6H2O), iron nitrate (Fe(NO3)3.9H2O), citric acid (C6H8O7) and nitric acid (HNO3) (purity 99.99%) were used to synthesize the CuCexFe2-xO4 (x=0, 0.02, 0.04, 0.06, 0.08 and 0.10) nanoferrites.

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2.2 Preparation of Samples

The CuCexFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) ferrite samples for CuCe spinel system were prepared using sol gel self-combustion hybrid route. The metal nitrates (with purity of 99.99%) of copper

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nitrate Cu(No3)3.H2O, cerium nitrate (Ce(NO3)2.6H2O) and iron nitrate (Fe(NO3)3.9H2O) were dissolved in HNO3. Molar ratios of the citric acid to nitrates were kept at 3:1. The ammonia was added to maintain the value of pH at ~8. The citric acid (C6H8O7) was used as a fuel due to low ignition temperature and better complexion ability as compared to others fuel used for the sol gel derived methods. The mixed solutions were stirred on stirrer at 250 rpm for 2 days. The stirred solutions were heated on the hot plate stirrer from room temperature to 80 °C with gradual increase in temperature and allowed to form gel. The viscous brown gel was then combusted on the hot plate stirrer by increasing temperature from 80 to 110 °C. The combusted gel was dried in the oven at 120°C for 48 hours for further removal of moisture. The dried powders were ground for 6 hours to get the fine powders of Ce-doped Cu nanoferrites. All CuCexFe2-xO4

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(x=0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) samples were sintered at 750°C for 6 hours with sintering conditions of 1–20°C/min using muffle furnace. 2.3 Characterizations X-ray diffraction patterns for CuCexFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) samples were taken using X-ray Diffractometer (Bruker D8 advance). The CuKα radiation with wavelength of 1.5406 Å was

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used. The scanning rate or step size was 0.05°/second respectively. The phase, crystalline structure, and purity of Ce-doped Cu nanoferrites samples were determined from the XRD patters. In addition to this, various others parameters such as inter planer spacing 'd', theoretical and experimental lattice parameters, hoping lengths at lattice sites (bond lengths), the mean ionic radii of A and B sub lattices (RA and RB) were also calculated using XRD data.Fourier transform infrared spectroscopy was used to find out the phase,

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structure and vibrational bands information. The FTIR analysis was done using KBr pellet method with Shimadzu 8400S IR spectrometer. Thermo gravimetric and differential thermal analysis was also done for the prepared samples. The morphology and grain size were calculated using FESEM (SUPRA 55VP

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ZEISS). The room temperature magnetic properties such as remanent magnetization (MR), saturation magnetization (Ms) and coercivity (Hc) of CuCe nanocrystalline ferrites were calculated using VSM-model LakeShore/7404. In addition, LoA (Law of approach to saturation) was applied to M-H loops for the determination of the maximum saturation magnetization of Ce-doped Cu nanoferrites samples.

3. Results and Discussion

3.1.1 X-ray Phase Analysis

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3.1 Materials Characterization

The staked XRD patterns of CuCexFe2-xO4(x=0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) nanoferrite samples are depicted in Figure 1. The phase, structure, crystallite size, lattice parameter and cell volume are determined from the staked XRD of the Ce-doped Cu nanoferrites samples. The crystallite size 'd', lattice parameter 'a'

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and cell volume 'V' for cubic phase of the Ce-doped Cu nanoferrites samples are calculated using equations1 and 2 respectively [22];

(1)

=  (ℎ +   +  )

(2)

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 = / 

Whereas, λ = wavelength of incident radiation, ω = FWHM (Full width at half maximum), θ = Bragg’s angle and Kis the crystallite shape and is equal to 0.89. Figure 1a shows the single phase structure of Cu ferrite in the absence of Ce contents at the sintering temperature of 750 oC. The peaks were matched using ICDD cards # 00-08-0234, 00-048-00491 and 00-520277 respectively. However, it can be seen that by the addition of Ce contents (x=0.06), the extra peak was observed. The peak is matched with the ICDD card # 96-900-9009 and corresponds to CeO2. X-ray scanned from 20-30 degree is depicted in Figure 1B. Figure 1B shows the slow X-rays scan which does not

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reflect strong peaks for the impurities in the scanned XRD patterns. However, small background noises were detected as shown in the Figure 1B respectively. In addition, the arrangement of the atoms, geometry and size of the unit cell can also be calculated from the relative intensities of the diffraction peaks. The different contents of the Fe3+ and Ce3+ in spinel structure result in the variations of peak intensities which are due to the variations of metal cations at the A and B

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sites respectively. In our current study, it is noticed that with the systematic increase in the Ce concentration the intensity of the peak is increased. Accordingly, it is also observed from the XRD patterns that the major cubic phase peak (311) shows decrease in intensity of the peak. Thus, the other peaks also show deceased intensities except the CeO2 peak. The intensity of the peaks was decreased but major peaks exist which is the confirmation of spinel phase. Therefore, the variations occurred in the peak intensities are

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speculated due to the migration of Ce and Fe ions in tetrahedral and octahedral (A and B) sites in spinel structure [23]. The variations in the peak intensities represented the variations in the spinel structure which may have potential applications due to the different magnetic properties. Table 1 depicted the parameters

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calculated from the XRD data of the Ce-doped Cu nanoferrites samples. The variations in the theoretical and experimental lattice parameter, crystallite size and volume of the cell are presented in Figure 2 (a,b). The values of the crysstallite sizes calculated from Sherrer formula was in the range of 25 to 91 nm. It is found that the crystallite size decreased as the Ce3+ contents increased in the Cu nanocrystalline ferrite. Similarly, the lattice parameter and unit cell volume correspond to decrease in the Ce-doped Cu nanoferrites samples. It is also investigated that increase in the lattice strain is because of the decrease in crystallite size. The mean ionic radii of A and B sub lattices (site radii-RA and RB),hoping lengths at lattice

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sites (bond lengths) of the Ce-doped Cu nanoferrites are also determined from the X-ray diffraction data by using Bertaut method [24] followed by the equations;  =  − 1/4 √3 − "# &

$ = %' − ( − "#

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(4)

+

") = √3* + 

(5)

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'

", = 

/0 =

'

+

+-

1√1

(3)

.

− + 3* 

(6)



() + , ) + √3(, + "# )

(7)

Where, U is the positional parameter for the spinel ferrite (0.381Å),Uideal is (0.375°A), δ

= U −Uideal , δ is

the deviation of the oxygen parameter and Ro = radius of the oxygen ion=1.35Å. Table 2 presented the calculated values of cation distribution at rA, rB, RA and RB for CuCexFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) nanocrystalline ferrites. The unshared (dBEU) and shared edges (dAE, dBE) are also measured using the following relations [24];

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)2 = √2(2 − . 5)

(8)

,2 = √2(1 − 2)

(9)

,26 = 7(4  − 3 + 11/16)

(10)

The calculated values of unshared (dBEU) and shared edges (dAE, dBE) are listed in Table 2. The site radii and

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bond hoping lengths depend on the substituted metal ions. Site radii and bond length for Ce-doped Cu nanoferrites samples are found to be decreased by increasing the Ce3+contents in spinel lattice. Table 2 depicted the variations of rA,rB, RA and RB. Site radii rA decreases from 0.5482 to 0.5186 whereas rB increases from 0.6913 to 0.6595 as the Ce3+ ions increased. However, hoping lengths RA decreased from 1.8982 to 1.8686 and RB decreased from 2.0425 to 2.0107 respectively. These site radii and bond hopping

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lengths are in agreement with the previous studies [25]. Ce ions replaced the Fe ions which has small ionic radii as compared to Ce which produces the vacancies in the spinel lattice as concentration of Cu increased. As the concentration of Cu increases in spinel lattice, it replaces Fe ion which has small ionic radii

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corresponds to increase in site radii and bond length respectively [26-27]. Theoretical analysis predicts that the variations in the structural properties are mainly depends on the oxygen positional parameters, doping of metal cations and ionic radii of the Ce-doped Cu nanoferrites systems.

3.1.2 FTIR Spectroscopic Analysis

FTIR analysis was performed to find out the structural and phase changes in the Ce-doped Cunanoferrites. Room temperature FTIR spectra of CuCexFe2-xO4 samples at x=0.00 and 0.10 are presented in Figure3. FTIR patterns showed the presence of spinel phase of prepared nanoferrites at 750 oC. At the frequency

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range of 400 cm-1 and 700 cm-1, two absorption bands are observed. These two absorption bands are due to the intrinsic stretching vibrations of oxygen and metal ions at tetrahedral and octahedral sites. The absorption band at 533 cm-1 is due to the lattice vibrations of the bonds of iron and oxygen (Fe3+-O2-) at A sites. However, the low absorption band below 450cm-1 is attributed due to the lattice vibrations of iron and

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oxygen ions at B sites. The band at 1530cm-1 is due to the oxygen nitrogen stretching vibrations. On the other hand, the absorption bands at 2350 cm-1 and 650 cm-1 may be because of hydrogen oxygen stretching vibrations and Fe2O3 vibrations respectively [28].

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3.1.3 Thermo gravimetric Analysis (TGA) Thermo gravimetric analysis of the Ce-doped Cu nanoferrites was carried out to investigate the variations such as decomposition and dehydration which were produced during the heat treatment of the nanoferrites. TGA/DTA curves for the CuCexFe2-xO4at x=0.00 and 0.10 nanoferrites are presented in Figure 4 (a-b). Figure 4a shows the two major steps which confirm the maximum weight losses occurred at 100oC and at 450 oC. The weight loss at 100 oC is due to the removal of residual water in nanoferrites. The weight loss at 450 oC is due to oxidation and decomposition processes respectively [29]. DTA curves show the behaviour of Cu ferrite with and without Ce and it may be attributed for the formation of spinel nanoferrites at sintering temperature of 750oC [30].

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3.1.4MicrostructuralAnalysis 3.1.4.1 SEM Analysis Field emission scanning electron microscopy was employed to observe the morphology, microstructure, shape and the grain size of the Ce-doped Cu nanoferrites. The line intercept method was used to find out

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the average grain size as given in equation 11[31]. Grain size= 1.5L/MN

(11)

Where L is the total length of the test in the FESEM micrographs, M is the magnification; N is the total number of intercepts and of the Ce-doped Cu nanoferrites. FESEM micrographs of CuCe (x=0, 0.06 and

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0.10) nanocrystalline ferrite are depicted in Figure 5 (a-c). The average grain size is in the range of 90 to 32nm which is in accordance with the crystallite size found using XRD. The grain size decreased as Ce concentration increased. This confirms that the each grain is the combination of many crystallites. The

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shapes of the grains for all concentration of Ce-doped Cu nanoferrites are spherical as shown in Figure 5a. The agglomerations in Ce-doped Cu nanoferrites samples are increased as Ce concentration increased as depicted in Figures 5 (a-c). This shows the nucleation and growth of nanocrystallites of Ce-doped Cu ferrites at large concentration of Ce contents which may be due to the dipole-dipole interactions of the nanoferrites in spinel structure [32].

3.1.4.2 TEM Analysis

Transmission electron microscopy (TEM) was also done to see the shape, morphology and the grain size of

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Cu nanoferrites and Ce-doped Cu nanoferrites respectively. Figure 6 (a-b) depicts the TEM graphs of the Cu nanoferrite (x=0) and Ce doped Cu nanoferrites (x=0.1). It can be seen that the Cu nanoferrite has larger grains as compared to the Ce doped Cu nanoferrites. However, the agglomerations occurred as the Ce concentrations are increased in Cu nanoferrites. The grain size was decreased with the doping of Ce

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contents in the Cu nanoferrites. The shape of the Cu nanoferrites was hexagon in shape whereas hexagon shape becomes distorted with the Ce concentrations in the Cu nanoferrites samples. 3.3 Magnetic Characteristics of Ce-doped Cu nanocrystalline Ferrites

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Magnetic characteristics were measured to find out the magnetic properties of the Ce-doped Cu nanoferrites. It was investigated that the substitution of cations, preparation method and sintering temperature were important parameters for distinct magnetic properties. To investigate the magnetic behaviour in Ce-doped Cu nanoferrites, recorded hysteresis loops were analysed. 3.3.1Magnetic Hysteresis Loops Figure 7 represent the hysteresis loops of Ce-doped Cu nanoferrites. The magnetic parameters such as remanence, saturation and coercivity are calculated from the M-H loops. Table 3 depict the calculated values of the saturation, magnetic squareness, remanence and coercivity of the magnetic loops of the Cedoped Cu nanoferrites. The magneto crystalline anisotropy constant (K) and Bohr magneton (µB) were also calculated using the following equations[33-34];

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Anisotropy constant =

9:×<=

Bohr magneton (@, ) =


(12)

>.?-

(13)

&&'&

Where 'M' is the molecular weight, 'Ms' is the saturation magnetization of the prepared Ce-doped Cu nanoferrites samples and 'Hc' is the coercivity calculated from M-H loops respectively.

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Figure 8apresents the behaviour of magnetic saturation and remanence whereas the coercivity, magnetic squareness, anisotropy constant and Bohr magneton are depicted in Figures 8b and 8c respectively.

The law of approach to saturation (LOA) were applied to calculate the saturation magnetization for Cedoped Cu nanoferrites samples. To find out the values of magnetic saturation from LoA, the corresponding data of saturation magnetization for each sample was fitted by using the least square methods and the E

M = Ms D1 − − F

G

FH

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equation is presented here [35]; I + χH

(14)

Where ′H′ is the applied field, ′χ′ is the magnetic susceptibility, 'Ms' is the saturation magnetization, 'A' is

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the in homogeneities present in the sample and 'B' is the anisotropy constant. Figure 9 (B-G) shows the fitted curves data for saturation magnetization measured by LoA. The saturation magnetization and remanence of the nanocrystalline ferrite was increased as the cerium concentration increased. This may be due to the well crystallites and better morphology of the Ce-doped Cu nanoferrites. The coercivity increases as the Ce3+ concentration increased which may be because of the secondary phases at the grain boundaries, production of grain growth and distortion in internal grains in Ce-doped Cu nanoferrites [36]. The coercivity increased as the grain size decreased which is in agreement with the inverse relationship of

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coercivity with grain size (Hc∞1/r).

Ce-doped Cu nanoferritesat x=0.00 shows the soft magnetic behaviour of the prepared nanoferrites. The magnetic hysteresis loops shows the variations in the magnetic properties due to the different morphology, single domain structure, magnetocrystalline anisotropy, grain size strains, single phase, lattice

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imperfections, dislocations and crystalline nature of the Ce-doped Cu nanoferrites [37-38]. However, the intrinsic and extrinsic properties of these Ce-doped Cu nanoferritesalso depend on the grain size, morphology, composition, synthesis method porosity, defects, and structure of the ferrites [39].

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Super exchange interactions are the most important factors for the variations in the magnetic properties of the nanoferrites. Therefore, the substitution of metal cations is one of the key elements to tune the magnetic properties of the spinel ferrites. The total magnetic moments of the materials depend on the interactions of total magnetic moments at lattice sites and the total number of metal ions. This can be explained according to the Neel's sub lattice theory. According to the theory, three types of interactions AA, AB and BB at lattice sites. However, AB interactions are the main interactions for the variation in magnetic properties [40]. It has been investigated that the larger ionic radii of the metal cations such as Cu and Ce as compared to Fe creates lattice shrinkage which also responsible for the electromagnetic losses and variations in the magnetic properties accordingly. Magnetocrystalline anisotropy and Bohr magneton were found to be increased with the Ce contents in the Cu nanocrystalline ferrite (Table 3).

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The variations in magnetocrystalline anisotropy and coercivity are due to the number of magnetic moments and domain walls. The increase in coercivity in Ce-doped Cu nanoferritesis also because of larger value of magnetocrystalline anisotropy of Ce3+ contents as compared to other metals cations. This could be explained on the basis of Stoner-Wolforth model for ferrites [41]. The calculated values of magnetic moments and magneto crystalline anisotropy are depicted in Table 3. It

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can be seen that the magnetic moments and anisotropy increased with increasing Ce3+ contents in Cu spinel ferrites. Moreover, the calculated values of magnetic saturation from LoA and hysteresis loops are also given in Table 3. It has been observed that the experimental data of Ms for each Ce-doped Cu nanoferrite sample has higher values as compared to experimental data observed from MH loops. Therefore, this may be the confirmation of samples saturated at infinite field. The fitted curves using LoA are presented in

applications due to variations in the investigated properties. 4. Conclusions

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Figure 9 (B-G) respectively. Ce-doped Cu nanoferrites with different substitution are suitable for various

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Ce-doped Cu nanocrystalline ferrites were prepared using sol gel self-combustion hybrid method.XRD, FESEM, TGA, DTA and FTIR were employed to investigate the structure, phase and morphology of Cedoped Cu nanoferrites samples. XRD analysis revealed the single phase structure of Cu ferrite whereas as the Ce contents increased from x=0.06, maximum peak intensity of spinel ferrite decreased. However, the increased extra peak intensity of CeO2 was observed as Ce3+ concentration increased. Spinel phase of the Ce-doped Cu nanoferrites was also confirmed from FTIR and TGA. The agglomerations in Cu samples increased as Ce3+ concentration increased. Saturation magnetization, remanence and coercivity increased as

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the Ce3+ contents increased in Ce-doped Cu nanoferrite samples. Further, the maximum value of saturation was calculated using law LoA. Ce-doped Cu nanosized ferrites with various properties may be promising material for core, security, sensing, switching, multilayer chip inductor, microwave absorption and

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[15] Melo RS, Silva FC, Moura KRM, De Menezes AS, Sinfronio FSM, Magnetic ferrites synthesised using the microwave-hydrothermal method. J. Magn.Magn. Mater., 2015, 381: 109–115. [16] Akhtar MN, Khan MA, Ahmad M, Murtaza G, Raza R, Shaukat SF, Asif MH, Nasir N, Abbas G, Nazir MS, Raza MR. Y 3 Fe 5 O 12 nanoparticulate garnet ferrites: Comprehensive study on the synthesis

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and characterization fabricated by various routes. J. Magn. Magn. Mater., 2014, 368: 393-400. [17] Gasgnier M, Ostorero J, Petit. A Rare earth iron garnets and rare earth iron binary oxides synthesized by microwave monomode. J. Alloy. Compd., 1998, 275: 41-45.

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[18] Woltz S, Hiergeist R, Gornert P, Russel C, Magnetite nanoparticles prepared by the glass crystallization method and their physical properties, J. Magn. Magn. Mater. 2006, 298: 7-13. [19] Opuchovic O, Beganskiene A, Kareiva A. Sol–gel derived Tb 3 Fe 5 O 12 and Y 3 Fe 5 O 12 garnets: synthesis, phase purity, micro-structure and improved design of morphology. J. Alloy. Compd., 647 (2015) 189-197.

[20] Ahmed MA, Ateia E, Salem FM. Spectroscopic and electrical properties of Mg–Ti ferrite doped with different rare-earth elements. Phys. B. Condens. Mater., 2006, 381: 144–155. [21] Zhao H, Zhang D, Wang F, Wu T, Gao. Modification of ferrite–manganese oxide sorbent by doping with cerium oxide. J, Process Saf. Environ. Prot., 2008, 86: 448–454.

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[22] Ji B, Tian C, Zhang Q, Ji D , YANG J, XIE J, Si J, Magnetic properties of samarium and gadolinium co-doping Mn-Zn ferrites obtained by sol-gel auto-combustion method, J. Rare. Earths., 2016, 34: 10171023. [23] Hashim M., Alimuddin, Shirsath SE, Kumar S, Kumar R, Roy AS, Shah J, Kotnal RK. Preparation and characterization chemistry of nano-crystalline Ni–Cu–Zn ferrite. J. Alloy. Compd., 2013, 549: 348–

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[24] Venkatesh D, Himavathi G, Ramesh KV. Structural, Magnetic, and Electrical Properties of Ni0. 65Zn0.35−xCuxFe2O4 Nanoferrite System, J. Supercond. Nov.Magn. 2015, 28: 2801-2807.

[25] Shirsath SE, Toksha BG, Kadam RH, Patange SM, Mane DR, Jangam GS, Ghasemi A. Doping effect of Mn 2+ on the magnetic behavior in Ni–Zn ferrite nanoparticles prepared by sol–gel auto-combustion.

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J. Phys. Chem. Solids., 2010, 71: 1669.

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magnetic behavior evaluation of Mg–Tb ferrite/polypyrrole nanocomposites. Ceram. Int., 2015 41: 651-

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[28] Akhtar MN, Khan MA, Raza MR, Ahmad M, Murtaza G, Raza R, Asif MH, Saleem M, Nazir MS. Structural, morphological, dielectric and magnetic characterizations of Ni0.6Cu0.2Zn0.2Fe2O4 (NCZF/MWCNTs/PVDF) nanocomposites for multilayer chip. Ceram. Int., 2014, 40: 15821-15829. [30] Mukhtar MW, Irfan M, Ahmad I, Ali I, Akhtar MN, Khan MA, Abbas G, Rana MU, Ahmad M. Pr-substituted MgZn ferrites for core materials and high frequency

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[32]W.A. Bayoumy, M.A. Gabal, Synthesis characterization and magnetic properties of Cr-substituted NiCuZn nanocrystalline ferrite, J. Alloy. Compd. 2010, 506: 205-209. [33] Kambale RC, Shaikh PA, Kamble SS, Koleka YD, Effect of cobalt substitution on structural, magnetic

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and electric properties of nickel ferrite. J. Alloy. Compd., 2009, 478: 599-603. [34] Akhtar MN, Sulong AB, Khan MA, Ahmad M, M. ALi, Islam MU. Impacts of Gd–Ce on the structural, morphological and magnetic properties of garnet nanocrystalline ferrites synthesized via sol–gel route. J. Alloy. Compd., 2016, 509: 5119–5126. [35] Grossinger R. A critical examination of the law of approach to saturation. I. Fit procedure. Physica Status Solidi (a)., 1981, 66: 665. [36] Al-Hilli MF, Li S, Kassim KS. Gadolinium substitution and sintering temperature dependent electronic properties of Li–Ni ferrite. Mater. Chem. Phys. 2011, 128: 127–132. [37] Yanmin Y, Jing J, Liangchao L, Yunlong X. Synthesis and Magnetic Properties of Nano-Sized Zn0.6Cu0.4Cr0.5SmxFe1.5-xO4 via Soft Chemistry Route. J. Rare Earths., 2007, 25: 228-231.

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[38] Mürbe J. Töpfer J. High permeability Ni–Cu–Zn ferrites through additive-free low-temperature sintering of nanocrystalline powders. J. Euro. Ceram. Soc., 2012, 32: 1091–1098. [39] Gabal MA, Al Angari YM, Al-Juaid SS. A study on Cu substituted Ni–Cu–Zn ferrites synthesized using egg-white. J. Alloy. Compd., 2010, 492: 411–415. [40] S. Chikazumi, Physics of Ferromagnetism, 2nd ed., Oxford Science Publications, 1997.

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[41] Gabal MA, Magnetic properties of NiCuZn ferrite nanoparticles synthesized using egg-white. Mater. Res. Bull. 2010, 45: 589–593. Figures Captions

Figure 1 XRD of CuCexFe2-xO4 nanocrystalline ferrites at (a) x=0.00, (b) x=0.02, (c) x=0.04, (d) x=0.06, (e)

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x=0.08 and (f) x=0.10

Figure 2(a) Theoretical and experimental lattice parameter and (b) Crystallite cell vs. volume of the cell of nanocrystalline ferrites at (a) x=0.00, (b) x=0.02, (c) x=0.04, (d) x=0.06, (e) x=0.08 and (f) x=0.10

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Figure 3 FTIR patterns of CuCexFe2-xO4 nanocrystallineferrites at (a) x=0.00 and (b) x=0.10 Figure 4 TGA/DTA of CuCexFe2-xO4 nanocrystalline ferrites at (a) x=0.00 and (b) x=0.10 Figure 5FESEM micrographs of CuCexFe2-xO4 at (a) x = 0.00, (b) x=0.06 and (c) x=0.10 nanocrystalline ferrites

Figure 6 TEM graphs of CuCexFe2-xO4 at (a) x = 0.00 and (b) x=0.10 nanocrystalline ferrites Figure 7 M-H Loops of CuCexFe2-xO4 nanocrystalline ferrites at (a) x=0.00, (b) x=0.02, (c) x=0.04, (d) x=0.06, (e) x=0.08 and (f) x=0.10

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Figure 8(a) Variation of saturation remanence (Mr), Magnetization (Ms) and (b) coercivity (Hc), magnetic squareness and (c) magnetic moment and magnetic anisotropy constant for Ce-doped Cu nanoferrites by sol-gel self-combustion hybrid route

Figure 9 Fitted curves of Ms calculated using LOA ofCuCexFe2-xO4nanocrystalline ferrites at (B) x=0.00, Tables Captions

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(C) x=0.02, (D) x=0.04, (E) x=0.06, (F) x=0.08 and (G) x=0.10

Table 1XRD parameters of CuCexFe2-xO4(x=0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) prepared by sol-gel self-

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combustion method.

Table 2 Site radii and bond length calculated from the XRD patterns CuCexFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08 and 0.10)prepared by sol-gel self-combustion method. Table 3 Magnetic parameters of CuCexFe2-xO4(x=0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) prepared by sol-gel self-combustion method.

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[111]

(a)

[311] [220] [222] [400] [200]

(A)

[422] [511] [440] [620]

[331]

(c) (d)

*

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Intensity Cnts (a.u)

(b)

ICDD # 96-900-9009

(a) 20

30

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(e)

10

* CeO2

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ICDD # 00-08-0234

40

50

60

70

2-Theta Scale

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* CeO2

[111]

(a)

Intensity Cnts (a.u)

(b)

(c)

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(d)

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(e)

20

*

(a)

22

24

26

2-Theta Scale

Figure 1 (A, B)

13

28

30

80

9.30

100

9.25

90

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8.38 aexp athe

9.20

80

9.15 9.10

a The

8.30

9.05

8.28

9.00

575

60

570

50

565

40

8.26

8.95

560

30

8.24

0.00

0.02

0.04

0.06

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8.90

0.08

0.10

0.12

Ce-concentrations (x)

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8.22 -0.02

Figure 2

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a exp

70

580

(b)

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8.32

585

14

20 -0.02

0.00

0.02

0.04

0.06

Ce-concentrations (x)

0.08

0.10

555 0.12

Volume of the Cell (oA)

(a) Crystallite size (nm)

8.34

Crystallite size (nm) Volume of cell (oA)

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8.36

590

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500

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% Transmission

(a)

1000

1500

2000

2500

3000 -1

Wave number (cm )

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Figure 3

15

3500

(b)

4000

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17.56 5

0

17.54

-5

17.53

Weight loss %

14.54

17.52

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-15

0

-5

17.51

-10

17.50

14.52

-20

-15

17.49

14.50

-25

100

200

300

400

500

600

o

Temperature C

700

0

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Figure 4 (a,b)

AC C

0

17.48

16

100

-20 200

300

400 o

Temperature C

500

600

700

DTA (uV)

14.56

DTA (uV)

Weight loss %

14.58

5

(b)

17.55

(a)

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14.60

(b)

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(c)

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Figure 5

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Figure 6

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18

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60 50

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a

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20 10 0

-20 -30 -40 -50 -60

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-10000

Magnetization (emu/g)

7

-10

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Magnetization (emu/g)

f e d c b

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-7

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Applied Field (Oe)

Figure 7

19

0

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Applied Field (Oe)

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0.80 Mr (emu/g) Ms (emu/g)

50

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Hc (Oe) Mr/Ms

0.75

45

(a)

800

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(b)

20

400

30 200

15

0.02

0.04

0.06

0.08

0.10

Ce-concentrations (x)

50000

40000

0

0.04

0.06

Ce-concentrations (x)

Figure 8(a-c)

20

0.08

0.10

0.06

Ce-concentrations (x)

10000

0.02

0.50

0.04

20000

EP 0.00

0.02

30000

3.5

3.0 -0.02

0.60

0.55

0.12

Anisotropy constt (k)

4.0

0.00

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(c)

4.5

0 -0.02

0.12

Magnetic moment (nB) Bohr Magneton Anisotropy Const.

5.0

Magnetic moment (nB)

0.00

AC C

10 -0.02

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25

0.65

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35

600

0.70

0.08

0.10

0.12

Mr/Ms

25

Hc (Oe)

40

Ms (emu/g)

Mr (emu/g)

30

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Ms a b chi

Data: Data1_C Model: LOA Weighting: y No weighting

37.0

Chi^2/DoF = 0.00008 R^2 = 0.99965

36.8

Ms (emu/g)

26.3

32.46945 ±1.98069 1702.37234 ±430.20829 -4077928.91906 ±1291491.33617 -0.00019 ±0.00007

37.2

26.2

26.1

36.4

36.2

25.9

36.0 8000

9000

10000

11000

12000

7000

Applied Field (Oe) 40.8

42.0

40.4

Chi^2/DoF = 0.00009 R^2 = 0.99965

40.2

Ms a b chi

Ms (emu/g)

40.0 39.8 39.6 39.4 8000

9000

45.5

10000

11000

41.6

Ms a b chi

55.815 ±5.08428 1986.4296 ±616.57715 -3971497.9682 ±1938180.7053 -0.00023 ±0.00019

44.0

43.5

12000

52.09418 ± 9.83684 1628.00256 ±1345.71277 -2767777.96803 ±4243936.28185 -0.00031 ± 0.00037

41.4 41.2

7000

8000

9000

10000

Applied Field (Oe) 48.5

48.0

47.5

Ms (emu/g)

Ms a b chi

11000

E

40.6

12000

AC C

Ms (emu/g)

44.5

12000

40.8

F

Chi^2/DoF = 0.0002 R^2 = 0.99978

11000

41.0

EP

45.0

10000

Data: Data1_E Model: LOA W eighting: y No weighting

Applied Field (Oe)

Data: Data1_F Model: LOA Weighting: y No weighting

9000

Applied Field (Oe)

Chi^2/DoF = 0.00073 R^2 = 0.99808

41.8

45.22834 ±3.50198 1156.38566 ±588.27902 -2323207.78392 ±1774495.07055 -0.00007 ±0.00013

7000

8000

M AN U

42.2

TE D

Ms (emu/g)

D

Data: Data1_D Model: LOA Weighting: y No weighting

40.6

41.35163 ±3.20181 1156.3859 ±588.27894 -2323208.53073 ±1774494.85294 -0.00006 ±0.00012

36.6

26.0

7000

Ms a b chi

C

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Chi^2/DoF = 0.00003 R^2 = 0.9994

26.4

Ms (emu/g)

B

Data: Data1_B Model: LOA W eighting: y No weighting

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26.5

G

Data: Data1_G Model: LOA Weighting: y No weighting Chi^2/DoF = 0.00022 R^2 = 0.99978 Ms a b chi

59.80179 ±5.44744 1986.42973 ±616.57713 -3971498.39652 ±1938180.6374 -0.00024 ±0.0002

47.0

46.5

43.0

46.0

45.5

42.5 7000

8000

9000

10000

11000

12000

7000

8000

9000

10000

Applied Field (Oe)

Applied Field (Oe)

Figure 9 (B-G)

21

11000

12000

Table 1

Sampl

d-

Crystallite

es (x)

spacing

size (nm)

0.02 0.04 0.06 0.08

0.1794

91.0

2.5207

0.2153

71.9

2.5131

0.2554

58.6

2.5027

0.2451

61.4

2.4831

0.3131

2.4831

0.3689

parameter(Å)

parameter (Å)

Cell

aexp

atheo

volume (A)

Lattice Strain %

8.3659

9.2605

585.52

0.138

8.3604

9.2462

584.37

0.172

8.3351

9.1805

579.08

0.204

8.3005

9.0906

571.90

0.215

46.6

8.2357

8.9223

558.61

0.268

25.5

8.2356

8.9220

558.59

0.485

AC C

EP

0.10

2.5224

Lattice

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0.00

Lattice

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FWHM

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Table 2

0.02 0.04 0.06 0.08

Shared edges

Unshared edges

dAE

dBE

3.0998

2.8158

2.9595

2.0412

3.0977

2.8140

2.9575

1.8912

2.0350

3.0884

2.8055

2.9486

0.6753

1.8834

2.0265

3.0755

2.7938

2.9364

0.5187

0.6595

1.8687

2.0107

3.0515

2.7720

2.9134

0.5186

0.6595

1.8686

2.0107

3.0515

2.7720

2.9134

rA

rB

RA

0.5482

0.6913

1.8982

0.5470

0.6899

1.8970

0.5412

0.6838

0.5334

AC C

EP

TE D

0.10

Bond length

SC

0.00

Site radii

RB

2.0425

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Site radii and bond length calculation of

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23

dBEU

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Mr (emu/g)

at x

Ms (emu/g)

13.48

26.38

0.02

28.07

36.87

0.04

29.60

40.33

0.06

31.74

42.11

0.08

32.93

44.99

0.10

33.17

Hc (Oe)

Magnetic moment/ formula unit (nB)

Anisotropy Const. (erg/cm3)

32.46

0.51

87.14

3.17

2394.53

41.35

0.76

91.23

4.30

3503.80

45.22

0.73

135.80

4.55

5705.01

52.09

0.75

372.61

4.60

16344.38

55..81

0.73

802.54

4.75

37610.70

0.66

936.39

5.07

48516.71

59.80

AC C

EP

49.74

Mr/Ms

from LOA

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0.00

calculated

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CuCexFe2-xO4

Ms

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Samples

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Table 3

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Graphical Abstract

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Magnetic Hysteresis loops of Ce doped Cu Nanoferrites

60 50 40

-10 -20 -30

a

7

Magnetization (emu/g)

0

EP

10

TE D

20

-40

AC C

Magnetization (emu/g)

30

f e d c b

0

-7

-50

-1000

-10000

0

1000

Applied Field (Oe)

-60

-5000

0

Applied Field (Oe)

25

5000

10000